Calculate cubic yards, bags, and Hillsboro OR-accurate ready-mix costs for any Washington County project. Includes Pacific Northwest rain guidance, Willamette Valley clay soils, 12-in. frost depth, wet-weather ACI 306 protocols, and ORSC 2021 compliance notes.
Enter dimensions for Hillsboro OR / Washington County volume, bags, and cost estimate.
Driveway: 4–5 in. min, 3,000 PSI per ORSC 2021. Hillsboro permit required. Compact clay subgrade to 95% Proctor — never pour on soft wet clay. 4 in. crushed rock base. No air entrainment. Avoid Nov–Mar pours if possible. Seal every 2–3 yrs.
Walkway 4 in · Driveway 4–5 in · Patio 4 in · Garage 4 in · Foundation 6 in · Footing 18–24 in (below 12-in. frost) · Industrial 6–8 in
Hillsboro is Washington County's largest city and one of Oregon's fastest-growing, home to 110,000+ residents and a massive high-tech industrial base anchored by Intel's largest campus in the world. Located in the Tualatin Valley at just 194 ft elevation, Hillsboro experiences a classic Pacific Northwest Marine West Coast climate — mild temperatures year-round but 161 rain days per year, making it the wettest city for concrete scheduling in this series. Willamette Valley soils are predominantly expansive clay-rich silt loam — highly moisture-sensitive and prone to shrink-swell cycles. Frost depth is 12 inches (Zone 8b), and occasional hard freezes November–February require ACI 306 cold-weather protocols on borderline-temperature pours.
Hillsboro averages 161 rain days per year — from November through March, rain is nearly continuous. Pouring concrete in active rain is almost always a mistake: rainwater dilutes the surface paste, raising the water-cement ratio and permanently weakening the top 1/4–1/2 inch of the slab. Surface scaling, dusting, and premature wear are the direct results. The golden rule for Hillsboro concrete: (1) Schedule all exterior pours May through September — Hillsboro averages only 14 rain days from June–August combined; (2) Never pour when rain is forecast within 8 hours; (3) Have poly sheeting staged and ready to cover the pour immediately if an unexpected shower arrives; (4) Drain the subgrade thoroughly before placing — saturated Willamette clay cannot be compacted and will pump under load, causing slab settlement; (5) Never pour directly on muddy, soft, or ponded subgrade — remove all saturated material and replace with crushed rock before placement. Hillsboro contractors routinely pump standing water from excavations before footing pours from October through April.
All flatwork: 3,000 PSI min (ORSC 2021); 4–5 in. driveways/patios; no air entrainment required for most residential flatwork (Zone 8b — mild freeze-thaw); frost depth 12 in. · Subgrade: Remove all organic topsoil and saturated clay; compact Willamette silt loam to 95% Proctor; 4 in. crushed rock base; slope grade away from structure for drainage · Cold weather Nov–Feb: ACI 306 — protect below 40°F with insulated blankets; avoid pours when forecast low is below 35°F · Wet weather: Never pour in active rain; have poly cover staged; drain subgrade completely · All OR contractors must hold valid Oregon CCB License — verify at oregon.gov/ccb.
Hillsboro's Willamette silt loam and Quatama clay loam soils are the defining subgrade challenge in the Tualatin Valley. These soils are highly moisture-sensitive — saturated in winter, hard and cracked in August — and have a high Plasticity Index (PI), meaning they expand significantly when wet and contract when dry. Before any Hillsboro slab, remove all organic topsoil (typically 6–12 in.), proof-roll the subgrade to identify soft zones, and compact to 95% Proctor density. Any soft spots should be undercut and backfilled with 3/4-in. crushed rock. Installing a French drain or perimeter drain around slabs in high-clay areas is strongly recommended to intercept lateral water movement and prevent long-term settlement.
Hillsboro is home to Intel's largest global manufacturing campus (Ronler Acres / Jones Farm) plus major facilities for Nike, Epson, and dozens of semiconductor suppliers — making it one of the top industrial concrete markets in the Pacific Northwest. Industrial and cleanroom-grade concrete in Hillsboro typically requires 4,000–5,000 PSI, F-number floor flatness specs (FF/FL ≥50/35), low-shrinkage admixtures, and polished or epoxy-coated surfaces. This drives a large, sophisticated ready-mix market with multiple batch plants operating in Washington County — good news for residential customers who benefit from frequent truck availability and competitive pricing despite the PNW premium.
Multiply length × width × (depth ÷ 12) for cubic feet, divide by 27 for cubic yards, add 10% overage. Major Hillsboro / Washington County suppliers include CalPortland, CEMEX, Knife River (CRH), Ash Grove / Martin Marietta, and Pacific Northwest independents. Short-load fees $100–$175 for under 3–5 cu yd. Book 24–48 hours ahead; November–March pours require same-day weather confirmation — most suppliers will reschedule at no charge for rain postponements.
Never pour concrete on saturated Willamette clay subgrade — slab settlement and cracking are virtually guaranteed. Never pour in active rain or within 8 hours of forecast rain. Footings must reach at least 18 inches below grade to clear the 12-in. frost depth with margin. Always remove organic topsoil and compact to 95% Proctor before any pour. Verify Oregon contractor licenses at Oregon Construction Contractors Board (CCB). Pull permits — Hillsboro inspectors verify subgrade prep, base compaction, and footing depth.
Washington County / Portland Metro ready-mix pricing is above the national average — Pacific Northwest labor costs, environmental compliance, and transportation from batch plants to suburban job sites push prices higher than desert Southwest markets. Intel and high-tech industrial demand keeps batch plants busy year-round, supporting good residential availability. No air-entrainment premium for most residential work.
| Mix / PSI | Hillsboro OR Price / Cu Yd | National Avg | Best For | Air Entrained? | ORSC 2021 |
|---|---|---|---|---|---|
| 2,500 PSI — Light | $142–$155 | $130–$148 | Light interior slabs only | Not Needed | Below Flatwork Min |
| 3,000 PSI — OR Standard ✓ | $150–$165 | $143–$158 | Driveways, patios, walkways | Not Needed | Compliant |
| 3,500 PSI — PNW Rec. | $158–$172 | $153–$166 | Wet-exposure slabs, patios | Not Needed | Compliant |
| 4,000 PSI — Structural | $165–$182 | $161–$173 | Foundations, heavy loads | Not Needed | Compliant |
| 5,000 PSI — Industrial | $182–$200 | $178–$193 | Intel / tech campus slabs | Per Engineer | Compliant |
| City | County / State | 3,000 PSI / Cu Yd | Frost Depth | Air Entrained? | Key Challenge |
|---|---|---|---|---|---|
| Hillsboro | Washington, OR | $150–$165 | 12 in. | Not Required | 161 Rain Days / Clay |
| Hayward CA | Alameda, CA | $158–$172 | None | Not Required | Seismic SDC-D / Bay Mud |
| Hesperia CA | San Bernardino, CA | $148–$162 | 18 in. | Recommended | Heat + Freeze / Caliche |
| Henderson NV | Clark, NV | $150–$163 | 6 in. | Not Required | 107°F Heat / Caliche |
| Hialeah FL | Miami-Dade, FL | $145–$160 | 0 in. | Not Required | HVHZ + Salt + Water Table |
The City of Hillsboro Building Division requires permits for new driveways, patio slabs, foundations, and retaining walls. Apply at hillsboro-oregon.gov/building. Standard permits process in 5–10 business days; online permits available for simple residential work. Inspectors verify organic soil removal, subgrade compaction, crushed rock base depth, and footing depth below frost line. Verify Oregon contractor licenses at Oregon CCB.
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